Process of treating peat for the production of fuel and the recovery of the by-products



' UNITED STATES PATENT OFFICE.

CARL ADOLPH SAHLSTRCM, OF OTTAWA, CANADA.

PROCESS OF TREATING PEAT FOR THE PRODUCTION OF FUEL AND THE RECOVERY OFTHE BY-PRODUCTS Specification of Letters Patent.

' Patented Aug. 1, 1905.

Application filed December 1, 1902- Serial No. 133,493.

To all whom it may concern):

Be it known that I, CARL ADoLPH SAHL- sTRoM, professor, of the city ofOttawa, in the county of Carleton, Province of Ontario, Dominion ofCanada, have invented certain new and useful Improvements in Processesof Treating Peat and Like Substances for the Production of Fuel and theRecovery of the By-Products, of which the following is a specification.

My invention relates to improvements in processes for treating peat,sawdust, and other vegetable matter for the production of fuel and therecovery of the useful by-products;

and the objects of my invention are to obtain roots, stalks, &c., fromwhich it is diflicult to extract the moisture,and,further,they containin their composition a very small percentage of combustible elements,and hence are of little value for the purpose of fuel. The peat powder,on the other hand, consists of vegetable matter in an advanced stage ofdecomposition. This powder is less bulky than the fiber and contains alarge percentage of carbonand other combustible substances and isconsequently of far greater value than th fiber as an economic fuel.

The object of my invention is therefore to separate the fiber from thepower,and,further, to remove from the powder such portions orconstituents as are non-combustible or are otherwise invaluable as fuel.In carrying out my process the moist peat from the bog is treated asfollows: The peat is first shredded or teased in order tobreak upthemeshes or intertwinings of the fiber. The result of thisstep of theprocess is that the moist peat is brought into a condition in which thefibers are more or less parallel, and consequently the moisture may bemore readily removed therefrom than when the grain or fiber of the peatis closely packed and running in all directions. The shredded peat isnow subjected in a continuous stream to a gradually-increasing pressurein such a manner that a very large quantity of the water contained isforced out and the peat is left partially dry and closely compressed.The compressed and partially-dried peat is now disintegrated andloosened without the fiber being broken, out up, or otherwise destroyed.In its disintegrated state the peat is subjected to heat at acomparatively low temperature, and by this means the water which isstill held by the peat is driven off in the form of steam and a certainamount of wood spirit or alcohol is also vaporized and driven off fromthe peat. This wood-spirit is collected and suitably stored for use. Thepeat is now thoroughly dry, and the next step of the process is toseparate the comparatively useless fiber from the powder, which, asabove pointed out, contains a large percentage of combustiblesubstances. The separation of the fiber from the powder is effected byscreening, and the fiber is carried off to be used as desired. Theseparated peat powder is now subjected to heat at gradually-increasingtemperatures, and it is found that the substancessuch as ammonia, aceticacid, and certain gases, all of which are non-combustible are driven offat the lower temperatures. The ammonia is given off'at a lowertemperature than the acetic acid, and consequently each of theseby-products may be collected entirely separate from each other, so thatthey may be used without further treatment for the purpose ofseparation. As the temperature to which the peat powder is subjectedincreases it will be found that certain tarry vapors and combustiblegases are given off. These combustible gases may be used as fuel for thepurpose of heating the peat powder, thus effecting a great saving inthecourse of carrying out the process. A further use for the tarryvapors and combustible gases will be hereinafter described. The peatpowderis now practically reduced to carbon. The impurities contained bythe carbon are, however, at this stage of the process almost entirelycombustible gases, hydrocarbons, and the like, which are valuable asfuel and may therefore be retained without detracting from the calorificpower of the fuel. If it be desirable to produce pure carbon, the powdermay be further heated, thus driving off the volatile impurities andleaving the carbon almost absolutely pure. The partially or completelycarbonized peat powder is now cooled by suitable means. It ispreferable, however, to commence cooling by passing steam through thehot mass, thus producing water-gas, which may be used as fuel to effectthe carbonization and to supply power for the various other steps of theprocess. The carbonized powder is then further cooled by bringing it inclose proximity to but not in contact with a continuous stream of coldwater. The tarry vapors and combustible gases which were extracted fromthe peat powder during the carbonizing process may now be added to thepartially-cooled carbon. The combustible gases will be absorbed by thecarbon as it cools, and the tarry vapors will be mixed with the powderand will serve as a binding material, so that the powder may be pressedinto briquets of suitable form. If, however, it is desirable to use thecarbonized peat in the form of powder instead of briquets, the tarryvapors need not be added; but the carbon may be finely powdered, and inthis state it may be very advantageously employed by blowing it into thefire-grate where it is to be used by any suitable blower. It will now beseen that by means of the process above described all the ingredients ofthe raw peat which are non-combustible or would tend to prevent theperfect combustion of the combustible portions are removed, theresultant product being a fuel which contains nothing buthighly-combustible substances and is consequently of great value.

Particular attention may be drawn to the greateconomy of the process,and it may here be pointed out that the entire process may be carriedout without the use of any outside fuel. The water-gas and combustiblegases produced as above described are more than sufficient to heat thepeat powder during its carbonization, and, further, in drying the peatit is not necessary to use any fuel, the hot gases which are theproducts of combustion of the Water-gas, &c., being used to dry thepeat.

I am aware that it is not broadly new to carbonize peat for the purposeof producing fuel, as this has been done to my knowledge more or lesssuccessfully on a number of different occasions; butI do claim as newthe combinations of steps hereinafter pointed out. Further, it may beparticularly mentioned that the partial carbonization of peat wherebythe noncombustible and useless substances-such as ammonia, acetic acid,and non combustible gasesare driven 013:, while the carbon andcombustible substancessuch as hydrocarbons, tarry vapors, and certaincombustible gases-are retained, is new.

What I claim as my invention is 1. The herein-described process oftreating peat and thelike which consists in first shredding or teasingthe raw peat; then subjecting the peat in a continuous stream to agradually-increasing pressure; then mechanically disintegrating thecompressed and partiallydried masses of peat without cutting ordestroying the fiber; then subjecting the peat to the action of heatwhereby the moisture is removed therefrom; then separating the fibrouspeat from the peat powder by screening; then subjecting the peat powderto heat atincreasing temperatures until the non-combustible ingredientsare driven off and the peat is reduced to a partially-carbonizedcondition in which it contains only the COll'llJllStiblG componentswhich are valuable as fuel; then cool ing the partially-carbonized peatas and for the purpose specified.

2. The herein-described process of treating peat and the like whichconsists in first removing the moisture therefrom; then separating thefibrous peat from the peat powder; then subjecting the peat powder toheat at increasing temperatures till the non-combustible ingredients aredriven otf thereby reducing the peat to a partially-carbonized conditionin which it retains all or part of the combustible components which arevaluable as fuel; then partially cooling the heated mass of more or lesscarbonized peat by passing a blast of steam therethrough, wherebywater-gas is produced as a by-product; then further cooling thepartially-carbonized peat as and for the purpose specified.

3. The herein-described process of treating peat and the likewhichconsists in first removing the moisture therefrom; then separatingthe fibrous peat from the peat powder; then subjecting the peat powderto heat at increasing temperatures till the acetic acid, ammonia andnon-combustible gases are driven oli"; then subjecting the peat to astill higher temperature whereby tar or tarry vapors and certaincombustible gases are driven off; then partially cooling the resultantproduct by passing a blast of steam therethrough, thereby producingwater-gas as a by-product; then further cooling the partially-carbonizedpeat by bringing it in proximity to but not in contact with a continuousstream of cold water, and simultaneously mixing with the cooling mass asuitable quantity of tar or tarry vapors to serve as a binding materialand bringing the unused portion of the previously-separated combustiblegases in contact with the cooling mass whereby such gases are absorbed;then pressing the resultant product into briquets of suitable shape andsize as and for the purpose specified.

4. The herein-described process of preparing peat and the like forcarbonization which consists in first shredding or teasing the moist rawpeat thereby breaking up the meshes and intertwinings of the fiberwhereby the moisture may be more readily extracted; then subjecting thepeat in a continuous stream to a grad uall y-increasing pressure wherebya large portion of the moisture is extracted therefrom; thenmechanically disintegrating the pressed and partially-dried peat; thensubjecting the mechanically-disintegrated peat to heat thereby removingthe remaining moisture; then screening the dried peat whereby vaporspreviously extracted, to serve as a binding material, and the unusedportion of the previously-extracted combustible gases which are valuableas fuel; then pressing the more or less carbonized mass into briquets asand for the purposespecified.

Signed at the city of Ottawa, in the Province of Ontario, this 27th dayof November, 1902.

CARL ADOLPH SAHLSTROM.

.Witnesses:

ARTHUR J. FORWARD, S. LURENA FARRELL.

